Current steering knob base designs for disabled drivers are configured in one of two ways. Both designs greatly restrict the user's freedom by allowing disabled persons to drive only specially equipped vehicles because of the permanent nature of the base systems.
The first style of mounting system consists of a base and one or two bands that wrap around the steering wheel. To install this type of device, the base must be held against the steering wheel while the bands are located and properly tightened around the steering wheel rim. This type of device usually needs to be installed by a professional with the aid of two hands and tools. This style of attachment usually damages the cover of the steering wheel rim.
The second mounting system is designed to span the inside diameter of the steering wheel. This device is adjusted by rotating a threaded rod to the proper length. Since this style of steering device spans across the steering wheel it interferes with air bag deployment. This style will not work on steering wheels in which the center portion of the wheel is raised and interferes with the device.